[Bug fortran/54758] New: accessing gcc builtins from fortran

[Joost.VandeVondele at mat dot ethz.ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54758

             Bug #: 54758
           Summary: accessing gcc builtins from fortran
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Joost.VandeVondele@mat.ethz.ch


I would like to experiment with prefetching in Fortran code (beyond
-fprefetch-loop-arrays). A convenient way to do this would be access the
gcc_builtins. I tried this the following way:

  INTERFACE
    SUBROUTINE builtin_prefetch(a) BIND(C,name="__builtin_prefetch")
      USE ISO_C_BINDING, ONLY: C_FLOAT
       REAL(KIND=C_FLOAT), dimension(*) :: a
    END SUBROUTINE
  END INTERFACE
  real*4 :: data(100)
  DO i=1,100
     CALL builtin_prefetch(data(i))
     data(i)=0
  ENDDO
END

but it didn't work... 

test.f90:(.text+0x36): undefined reference to `__builtin_prefetch'

no surprise, I guess, but it would be cool if it did.